To achieve an error-free data transmission over a single data path at very high data rate (especially when the rate is approaching the operating speed limit of the electronics of a data transmitter and receiver), the problem of accurately synchronizing the received data with the receiver local clock must be overcome. Previously, this problem was handled by encoding the data prior to its transmission with a timing signal of higher frequency than the data rate. The receiver, by analog means, then decoded the received signal back into data and the timing signal. The regenerated timing signal was used as the local clock for the data reception and/or data retransmission back to the transmission medium if the receiver was part of a data bus system. This previous approach has two main disadvantages:
(1) The timing signal encoding the data must be of higher frequency than the data rate. Because of this, the data rate remains significantly lower than the bandwidth of the transmission medium; and
(2) In a data bus system the number of stations to be connected on the bus is limited. The clock which is extracted from the decoded data is used to retransmit the data back to the medium. This approach accumulates distortion on both the data and the clock because each is used in a closed loop to generate the other.